Metal working machine liquid filtering device with coalescer, filter, and time delayer

ABSTRACT

Versatile filtering apparatus is provided, particularly for processing liquid or coolant used with metal-working machines. The apparatus is adaptable for processing coolant in a wide variety of coolant systems to meet a variety of requirements of metal-working machines in a plant. The apparatus includes a dirty liquid tank in side-by-side relationship with a clean liquid tank, a coalescing unit, a filtering unit, an automatic supply or fill valve for supplying liquid to the apparatus from the coolant system, and an automatic discharge valve for supplying processed liquid from the apparatus back to the coolant system. The coalescing unit separates free oils from the liquid and the filtering unit separates solid particles from the liquid. The processed liquid is then discharged back to the coolant system along with fresh coolant. The overall processing time, along with the time for operating the coalescing unit and the filtering unit, can be changed to adapt the filtering apparatus to meet the particular requirements of particular coolant systems.

This invention relates to versatile filtering apparatus which isparticularly adapted for use with a wide variety of coolant systemsemployed with metal-working machines.

Coolant systems for metal-working machines in plants or factories varywidely. There may be any from a few to a couple of dozen machines withwhich one coolant system is employed and the individual metal-workingmachines may have individual reservoirs or a single large reservoir maysupply some or all of the machines. The nature of contamination of thecoolant in the coolant system also varies widely. With some operations,the coolant becomes highly contaminated with oil from the machines andsolid particles are of little concern while in other systems,contamination of the coolant by solid particles represents a substantialproblem and relatively little oil contamination occurs from themachines. In any system, some of the coolant is lost during themachining operations and the coolant must be supplemented. In otherinstances, certain special additives in the coolant must be replenishedfrom time to time.

The present invention provides filtering apparatus of a highly versatilenature, being able to accommodate coolant systems employed with few ormany metal-working machines and being capable of handling particularcontamination problems incurred with particular metal-working systems.The filtering apparatus features automatic fill and discharge valveswhich render the overall coolant processing operation automatic, withonly periodic maintenance being necessary.

The filtering apparatus includes a dirty liquid or coolant tank and aclean liquid or coolant tank, preferably in side-by-side relationship. Acoalescent unit is also employed and can be mounted above the dirtyliquid tank to save floor space and to facilitate the flow of thecontaminated liquid to and from the dirty tank. This unit separates thefree oil from the liquid or coolant. The filtering apparatus furtherincludes a filtering unit which is preferably located beside andslightly above the dirty liquid tank, which facilitates flow of liquidto and from the dirty liquid tank. The filtering unit removes solidparticles from the liquid or coolant, such particles commonly being inthe nature of metal shavings or the like from the parts being processedby the metal-working machines. The pumps and valves supplying thecoalescing and filtering units can be timed so that the coalescing unitis operated longer when free oil in the coolant is more of a problem andthe filtering unit can be operated longer when solid particles in thecoolant are more of a problem.

In accordance with the invention, an automatic discharge valve suppliesthe liquid or coolant from the clean liquid tank back to the coolantsystem after the processed, clean liquid or coolant in the clean tankreaches a predetermined level therein. An automatic supply or fill valvesupplies dirty liquid from the coolant system to the dirty liquid tankat a predetermined time after the discharge valve has supplied theliquid or coolant from the clean tank back to the coolant system. Thisperiod of time may be from a matter of a few minutes to several hours,depending on the size and other requirements of the coolant system. Theentire filtering process is thereby automatic with no operator beingnecessary. Only occasional inspection and the usual periodic maintenanceare required.

It is, therefore, a principal object of the invention to providefiltering apparatus for coolant systems employed with metal-workingmachines, which apparatus is more versatile and automatic in operationthan those heretofore known.

Another object of the invention is to provide filtering apparatuscapable of use with a wide variety of metal-working machines.

Yet another object of the invention is to provide filtering apparatuscapable of handling liquids of widely varying quantities andencountering different types of contaminants, and doing so with minimalrequirements for an operator.

Yet a further object of the invention is to provide filtering apparatusembodying units for removing oil and solid contaminants from coolant andfor supplying the coolant automatically from a coolant system and backto the system.

Many other objects and advantages of the invention will be apparent fromthe following detailed description of preferred embodiments thereof,reference being made to the accompanying drawings, in which:

FIG. 1 is a somewhat schematic overall view in perspective of filteringapparatus in accordance with the invention;

FIG. 2 is a somewhat schematic top view of a coalescing unit of theapparatus of FIG. 1;

FIG. 3 is a somewhat schematic view in vertical section of a filteringunit of the apparatus in FIG. 1;

FIG. 4 is a schematic and diagrammatic view of the apparatus of FIG. 1showing piping, pumps, valves, and controls used therewith; and

FIG. 5 is a diagrammatic view of a coolant system with which theapparatus can be used.

Referring particularly to FIG. 1, filtering apparatus in accordance withthe invention is indicated at 10. For clarity in illustration, piping,pumps, and valves, including automatic fill and discharge valves areshown in a separate figure, FIG. 4, and will be discussed subsequently.The filtering apparatus 10 basically includes a dirty liquid or coolanttank 12 and a clean liquid or coolant tank 14 which preferably are inside-by-side relationship and separated by a common wall or partition16, which terminates below the other wall forming the tanks.

A coalescing unit 18 is employed to remove free oil from the coolant,which oil is received in the coolant from the metal-working machineswith which the coolant system is employed. As shown, the coalescing unit18 is mounted above the dirty liquid tank 12, which saves floor spaceand facilitates the flow of dirty coolant to and particularly from theunit. The processed liquid from the coalescing unit 18 can flow back tothe dirty liquid tank 12 by gravity.

A filtering unit 20 is mounted beside and slightly higher at its upperextremity than the dirty liquid tank 12. The filtering unit 20 removessolid particles from the coolant. These particles are usually metalchips received in the coolant contained in the coolant system from themetal-working machines. The position of the filtering unit 20 alsorenders the overall filtering apparatus 10 more compact and overflowliquid in the filtering unit 20 can flow back into the dirty liquid tank12 by gravity.

A main control panel 22 is mounted adjacent an end of the clean liquidtank 14 opposite dirty tank 12 and an auxiliary control panel 24 islocated adjacent the main panel 22.

With this compact arrangement, the entire filtering assembly 10 can bemounted on a common, single platform 26 to enable the entire apparatusto be fabricated at one location and moved as single piece of equipmentto the plant or factory where the apparatus will be employed. Theapparatus can also be moved to different locations in the plant orfactory as needs change.

The coalescing unit 18 can be of the type shown in our U.S. Pat. No.4,717,475, issued Jan. 5, 1988, and will not be discussed in greatdetail. Referring to FIGS. 1 and 2, the unit 18 includes a main tank 28with an oil chamber 30 at one side thereof and a processed liquid orcoolant chamber 32 at one end thereof. The chamber 30 communicates withthe main tank 28 through a slot 34 in an upper portion of a commonpartition 36 so that oil floating on the liquid in the tank 28 canoverflow through the slot 34 and into the chamber 30 The oil can besubsequently removed from the chamber 30 through a pipe 38 and amanually-operated valve 40 (FIG. 2). The coolant chamber 32 is separatedfrom the main tank 28 by a common baffle or partition 42 which stopsshort of the bottom of the tank so that liquid or coolant, relativelyfree of oil, can flow under the baffle 42 and into the chamber 32. Theliquid or coolant in the chamber 32 can then be discharged through adischarge pipe 44 (FIG. 4) extending upwardly therein with an open top.Liquid flowing through the top of the discharge pipe 44 is thendischarged by gravity back into the dirty liquid tank 12. The pipe 44preferably has an upper, adjustable sleeve thereon so that the level ofliquid in the chamber 32 can be varied and regulated. The coolant andoil are separated from one another in the tank 28 by oleophilic bodieswhich are located in coalescent cells 46. These are individuallyremovable from the main tank 28 so that the oleophilic bodies can becleaned from time-to-time. The dirty liquid coolant to be processed issuppled through an end of the main tank 28 by a supply pipe 48. The pipe48 preferably supplies the fluid directly into an end of the first ofthe coalescent cells 46, as discussed more fully in the aforesaidpatent.

The filtering unit 20 is shown particularly in FIGS. 1 and 3 and is of atype known in the art, as shown in U.S. Pat. No. 3,087,620, issued Apr.30, 1963, by way of example. The filtering unit 20, which will not bediscussed in detail, includes a tank 50 with a porous support or grate52 located above the bottom of the tank to support a section of a strip54 of filter media. The filter strip 54 is carried from a supply spool56 to the bottom of the tank 50 and across the supporting grate 52 byspaced conveyor chains 58 having flight bars 60 extending therebetween.The chains 58 are moved by drive sprockets 62 which, in turn, are drivenby a suitable motor 64 (FIG. 1) and a suitable mechanical driveindicated at 66. The filter strip 54 is moved down the end of the tank50, across the grate 52, and up the other end of the tank 50 where itfalls into a receptacle 68.

The filter strip 54 is normally not moved continuously across the grate52. Rather, it is moved periodically through a timer, or else pressureacross the strip and grate are sensed and the strip is moved when thepressure differential exceeds a predetermined amount, indicating thatthe filter media has clogged to a predetermined degree. Filter pumps, tobe discussed subsequently, are shut off as the strip is moved.

The operation of the filtering apparatus 10 will now be discussed,particularly in connection with FIG. 4. An automatic fill or supplyvalve 68 is opened when a timer T-1 times out to supply dirty orcontaminated liquid or coolant from a coolant system CS through a supplyline 70 to the dirty liquid tank 12. The liquid supplied through theline 70 can be by gravity or by a pump, depending upon the particularinstallation. The supply valve 68 remains open until the level of liquidin the tank 12 is substantially filled, to a level L-1. This level issensed by a level sensor as is well known in the art or by a pressuresensor located in the bottom of the tank and actuated when the level orpressure reaches a predetermined value, which occurs when the liquid inthe tank reaches the level L-1.

When the dirty tank 12 is filled and the valve 68 is shut off, theliquid in the tank 12 is allowed to settle for a period to allow oil andscum in the dirty liquid to rise to the top. A supply pump 72 is thenactivated to supply the dirty liquid from a floating skimmer 74 locatednear the top of the tank 12 through a line 76 and to the supply line 48for the coalescing unit 18. The pump 72 is preferably of theair-operated diaphragm type which minimizes mixing the coolant and oilas it is supplied to the coalescing unit 18. The pump 76 is controlledby a timer to operate for a period of about twenty minutes to one hour,depending upon the amount of free oil suspended in the coolant.

At the end of that period of time, a level-control pump 78 for thefiltering unit 20 is operated. This pump supplies dirty liquid from anoutlet line 80 connected to a lower portion of the dirty liquid tank 12through a supply line 82 to an intermediate portion of the filter tank50. The tank 50 is supplied with the liquid at a rate such that itoverflows through an overflow trough 84 and back into the dirty liquidtank 12. This assures that the level of the liquid in the filtering tank50 is always at a constant level during the operation of the filter unit20.

After a period of time sufficient to assure that the filter tank isfull, a timer starts a filter pump 85. The pump 85 draws liquid from anoutlet line 86 communicating with the bottom of the tank 50 below thefilter strip 54. This supplies filtered liquid through a supply line 88to a three-way valve 90 and, initially, through a first branch line 92to the dirty liquid tank 12. The rate of flow of the level-control pump78 exceeds that of the filter pump 85, twenty-five gpm versus twentygpm, for example, so that the level of liquid in the filter tank 50always remains constant, at the overflow chute 84.

The coalescing unit 18 and the filtering unit 20 then are continued inoperation for a predetermined period of time which can vary anywherefrom one to eight hours, depending upon the extent of contamination ofthe coolant. At the end of this period, the three-way valve 90 isactuated to now supply the filtered liquid from the line 88 through asecond branch pipe 94 and into the clean liquid tank 14. The coalescingand filter units 18 and 20 continue to operate and the dirty liquid tank12 begins to empty until about half-empty, when a level L-2 is reached.A sensor then stops the diaphragm pump 72 and, of course, stops theoperation of the coalescing unit 18. The level in the dirty tank 12continues to drop until a level L-3 is reached near the bottom of thetank, at which time the level-control pump 78 is shut off. The filterpump 85 then continues to operate for a period of time sufficient toempty the filter tank 50.

At any time liquid is withdrawn from the clean tank 14 until the liquiddrops to a level L-4, a proportioning or make-up pump 96 is started. Thepump 96 is operated by the opening of a solenoid valve 98 which supplieswater from a source indicated at 100 through the pump. The pump 96 drawscoolant concentrate from a source such as a fifty-five gallon drum 102and supplies the water and fresh concentrate through a line 104, wherethey are partially mixed, to a static mixer 106. The mixer is a cylinderwith baffles therein to cause additional mixing of the water andconcentrate which are then supplied through suitable openings into theclean liquid tank 14. The output of the proportioning pump 96 is small,being in the order of five gallons per minute. This pump is operateduntil the clean liquid in the clean tank 14 reaches a level L-5.

As the clean tank 14 continues to receive liquid from the branch line94, the liquid in the tank rises to an upper level L-6. At this time, atimer T-2 is started to operate the proportioning pump 96 for apredetermined short period of time sufficient for the clean liquid inthe clean tank 14 to flow over the partition 16 and into the dirtyliquid tank 12. This assures that any contaminants on the surface of theliquid in the clean tank flow back into the dirty tank. At that time, anautomatic discharge valve 108 is opened, after the timer T-2 times out,to supply the clean coolant from the bottom of the clean tank 14 througha line 110 to a supply line 112 back to the coolant system CS. Thedischarge valve 108 is closed when the liquid in the clean tank 14reaches the level L-4. When the discharge valve 108 closes, it actuatesthe timer T-1 for a given period of time. This period of time can varyfrom as little as five minutes to three hours or more, depending uponthe size and needs of the coolant system. When the timer T-1 times out,it opens the automatic fill valve 68 and the cycle automatically beginsonce again, with no operator needed for the controls.

In many instances, it is desirable for additional additives to beapplied to the clean coolant. In such an instance, an additive line 114can supply additional material to the clean tank 14 by a pump 116communicating with a suitable source 118 of the additive. The pump 116can be actuated manually or programmed into the cycle, if desired.

Such additives can include micro-biocides, rust preventatives,surfactant packages, and metal-working fluid concentrates, by way ofexample.

A coolant system with which the filtering apparatus 10 can be employedis shown diagrammatically in FIG. 5. This includes a large reservoir orsettling tank 120 which supplies a number of metal-working machines 122.A pump 124 circulates the coolant from the reservoir 120 to the machines122 and back again and also supplies coolant to the filtering apparatus10 through the line 70 when the valve 68 is opened. The clean coolant isthen returned to the coolant system when the discharge valve 108 isopened, either by gravity or by another pump. Also, in many instances,the individual machine tools will have their own reservoirs. Eachreservoir can be emptied by a sump-sucker or pump which supplies thecoolant to the filtering apparatus. After processing, the coolant can bedischarged to the reservoirs of the metal-working tools.

Various modifications of the above-described embodiments of theinvention will be apparent to those skilled in the art and it is to beunderstood that such modifications can be made without departing fromthe scope of the invention, if they are within the spirit and the tenorof the accompanying claims.

We claim:
 1. Filtering apparatus for processing coolant, used withmetal-working machines, or other contaminated liquid, said apparatuscomprising a clean liquid tank, a dirty liquid tank in side-by-siderelationship with said clean liquid tank, a coalescing unit forseparating free oil and located, at least in part, above said dirtyliquid tank, said coalescing unit including a main coalescing tank,container means in said main tank, a multiplicity of oleophilic bodiesin said container means, a supply pipe communicating with said main tankfor supplying contaminated liquid thereto, said main tank having anupper opening through which free oil can flow, said main tank having alower opening through which liquid can flow, means defining a chambercommunicating with said lower opening for receiving liquid therefrom,and means forming a discharge opening in an upper portion of saidchamber through which liquid can be discharged into said dirty liquidtank, and a diaphragm pump having an inlet receiving liquid from anupper portion of said dirty liquid tank and having an outlet supplyingliquid to said supply pipe; a filtering unit located, at least in part,above the level of said dirty liquid tank, said filtering unit includinga filtering tank having a layer of filter media therein, a grate in saidfiltering tank supporting a portion of said filter media, said filteringtank having over-flow means at an upper portion thereof for directingliquid above a predetermined level in said filtering tank into saiddirty liquid tank, a filter pump having an inlet communicating with saidfiltering tank below said grate to receive filtered liquid and having anoutlet, a three-way valve communicating with said filter pump outlet andhaving a first branch pipe communicating with said dirty liquid tank anda second branch pipe communicating with said clean liquid tank, and alevel-control pump having an outlet communicating with a portion of saidfiltering tank above said grate and having an inlet communicating with alower portion of said dirty liquid tank; a proportioning pump forsupplying fresh liquid to said clean liquid tank, an automatic fillvalve for supplying contaminated liquid to said dirty liquid tank andfor stopping the supply of liquid thereto when the liquid thereinreaches a predetermined level, an automatic discharge valve having aninlet communicating with a lower portion of said clean liquid tank andan outlet communicating with a coolant system reservoir, control meansfor opening said discharge valve after liquid in said clean liquid tankrises to a predetermined upper level and for closing said dischargevalve after liquid in said clean liquid tank drops to a predeterminedlower level, and timing means for opening said automatic fill valve apredetermined period of time after said discharge valve is closed. 2.Apparatus according to claim 1 further comprising a plurality ofmetal-working machines, and means for supplying coolant from saidreservoir to said machines and through said automatic fill valve whensaid fill valve is open.
 3. Filtering apparatus according to claim 1characterized by a source of liquid additives and means for supplyingadditives from said source to said clean liquid tank.
 4. In combination,a coolant system comprising a coolant reservoir, a metal-workingmachine, means for supplying coolant from said reservoir to saidmachine, and means for supplying coolant from said machine to saidreservoir, filtering apparatus for processing the coolant, saidapparatus comprising a clean coolant tank, a dirty coolant tank, acoalescing unit for separating free oil from the coolant, means forsupplying coolant from said dirty coolant tank to said coalescing unit,means for supplying coolant from said coalescing unit to said dirtycoolant tank, a filtering unit for separating particles from thecoolant, means for supplying coolant from said dirty coolant tank tosaid filtering unit, means for supplying filtered coolant from saidfiltering unit to said dirty coolant tank and, alternately, to saidclean coolant tank, an automatic fill valve for enabling the supply ofcoolant from said coolant system to said dirty coolant tank and forstopping the supply of coolant thereto when the liquid therein reaches apredetermined level, an automatic discharge valve for enabling thesupply of clean coolant from a lower portion of said clean liquid tankdirectly to said coolant system when the clean coolant rises to apredetermined upper level in said clean coolant tank, and for stoppingthe supply of coolant to said coolant system after the coolant in saidclean coolant tank drops to a predetermined lower level, and time delaymeans for causing said automatic fill valve to enable the supply ofcoolant again to said dirty coolant tank a predetermined period of timeafter said discharge valve stops the supply of coolant to said coolantsystem.
 5. The combination according to claim 4 characterized by therebeing a plurality of metal-working machines and said coolant supplymeans supplies coolant to said plurality from said reservoir, and tosaid reservoir from said plurality.
 6. Filtering apparatus forprocessing coolant in a coolant system which comprises a coolantreservoir, a metal-working machine, means for supplying coolant fromsaid reservoir to said machine, and means for supplying coolant fromsaid machine to said reservoir, said filtering apparatus comprising aclean coolant tank, a dirty coolant tank, a coalescing unit forseparating free oil from the coolant, means for supplying coolant fromsaid dirty coolant tank to said coalescing unit, means for supplyingcoolant by gravity from said coalescing unit to said dirty coolant tank,a filtering unit for separating particles from the coolant, means forsupplying coolant from said dirty coolant tank to said filtering unit,means for supplying coolant from said filtering unit by gravity to saiddirty coolant tank to maintain the level of coolant in said filteringunit at a predetermined level, means for supplying filtered coolant fromsaid filtering unit to said dirty coolant tank and, alternately, to saidclean coolant tank, an automatic fill valve for enabling the supply ofcoolant from the coolant system to said dirty coolant tank and forstopping the supply of coolant thereto when the liquid therein reaches apredetermined level, an automatic discharge valve for enabling thesupply of clean coolant from a lower portion of said clean liquid tankdirectly to said coolant system when the clean coolant rises to apredetermined upper level in said clean coolant tank, and for stoppingthe supply of coolant to said coolant system after the coolant in saidclean coolant tank drops to a predetermined lower level, and time delaymeans actuated when said automatic discharge valve stops the supply ofcoolant to said coolant system for causing said automatic fill valve toenable the supply of coolant again to said dirty coolant tank a periodof time after said discharge valve stops the supply of coolant to saidcoolant system.
 7. Filtering apparatus according to claim 6characterized by a source of coolant additives and means for supplyingadditives from said source to said clean coolant tank.